Liquid crystal displays are commonly used as display devices for compact electronic apparatuses, because they not only are very thin but also provide good quality images with little power.
A typical LCD device includes a liquid crystal display panel, and a backlight module disposed adjacent to the liquid crystal display panel. A plurality of source electrodes and a plurality of gate electrodes are disposed on the liquid crystal display panel. Each source electrode includes a source electrode driving integrated circuit (IC). Each gate electrode includes a gate electrode driving IC. An FPC is generally used in an LCD device for joining the liquid crystal display panel and a printed circuit board (PCB).
Referring to FIG. 6, a conventional LCD 100 includes a liquid crystal display panel 11, a backlight module 150 disposed adjacent to the liquid crystal display panel 11, a frame 160 containing the backlight module 150, a PCB 130 disposed adjacent to the frame 160, an FPC 1 joining the liquid crystal display panel 11 and the PCB 130, and a driving IC 15 disposed on the FPC 1.
Referring to FIG. 7, the FPC 1 includes a substrate 10, a plurality of input lines 120, a plurality of output lines, 140, and a resin layer 16. The substrate 10 includes a first joint part 12 for joining to the PCB 130, and a second joint part 14 for joining to the liquid crystal display panel 11. The input lines 120 are formed on the first joint part 12. The output lines 140 are formed on the second joint part 14. The input lines 120 and output lines 140 are electrically conductive.
The driving IC 15 is disposed in a middle region of the substrate 10. The input lines 120 of the FPC 1 are joined to the PCB 130, and are also joined to the driving IC 15 for signal transmission from the PCB 130 to the driving IC 15. The output lines 140 of the FPC 1 are joined to the liquid crystal display panel 11, and are also joined to the driving IC 15 for signal transmission from the driving IC 15 to the liquid crystal display panel 11. The resin layer 16 covers areas of both the input lines 120 and the output lines 140 that are around the driving IC 15. An aligning mark 18 is formed beside the output lines 140.
The input lines 120 and the output lines 140 are all rectangular, and a certain distance must be provided between each two adjacent input lines 120 and each two adjacent output lines 140 in order to avoid short circuits. When the number of driving signals is large, the areas of the first joint part 12 and the second joint part 14 must be correspondingly large in order to contain the large number of input and output lines 120, 140 that are needed for providing the large signal bandwidth. This results in a correspondingly very wide FPC 1, and may render the LCD 100 unsuitable for certain compact electronic apparatuses.
What is needed, therefore, is a flexible printed circuit and a liquid crystal display device using the same that overcome the above-described deficiencies.